docs: def add_section(self, id_, parent_id, section_type, points):
          '''add a section
  
          Args:
              id_(int): identifying number of the section
              parent_id(int): identifying number of the parent of this section
              section_type(int): the section type as defined by POINT_TYPE
              points is an array of [X, Y, Z, R]
          '''
          # L.debug('Adding section %d, with parent %d, of type: %d with count: %d',
          #         id_, parent_id, section_type, len(points))
          assert id_ not in self.sections, 'id %s already exists in sections' % id_
          self.sections[id_] = BlockNeuronBuilder.BlockSection(parent_id, section_type, points)